Caster



(No Model.)

D. J. POWERS.-

GASTER.

Patented Feb. 24, 1885,

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DAVID J. POWVERS, OF CHICAGO, ILLINOIS.

CASTER.

SPECIFICATION iorrning part of Letters Patent No. 313,023, dated February 24-, 1885.

(No model.)

T all whom it may concern.-

Be it known that I, DAVID J. POWERS, a citizen of the United States, residing at Ohica-go, in the county of Cook and State of Illinois, have invented new and useful Improvements in FurnitureCasters, of which the following is a specification.

I am aware that casters haveheretofore been provided with rollers of various kinds placed between-the plates to reduce or obviate frie tion, and therefore I do not claim rollers so placed, broadly, but confine myself to rollers v of a form and quality ashereinafterdescribed;

but that my improvement may be fully understood I will set out the difference between it and the several kinds which have preceded it. First, the merit of spherical rollers is in their perfect freedom of rotation in any and all directions, and freedom to shift the position of the axis of rotation as to the substance of the roller; but this quality depends upon per feet sphericit-y, which is difficult and costly to attain. Unless these rollers are truly spherical, they soon find a position where the imperfect form causes them to cease to rotate. Conical rollers constantly grind against the exterior rim or flange of the inclosing-plate. This not only causes great frictional resistance, but constantly tends to move the axis of rotation out of its radial position and cause the roller to jam and stick. Rollers which are sections of spindles, or cigar-shaped, be cause they present small areas of contact with the bearing-plates, are more easily disturbed as to their axial position than conical rollers. Rollers which are thin parallel-sided disks necessarily stand in their grooves tangential to the curve of said groove, and therefore with the principal frictional points at their peripheral angles, whereby their direction of progression will be constantly changed.- These practical defects have been remedied by p1acing each roller, of whatever shape, upon an ax ial spindle; but this of itself adds so much labor and cost in perforating each roller and in constructing and mounting the spindle that it is rendered impracticable.

My invention obviates all the practical disadvantages alluded to above as adherent to the art prior to this time by employing cast-metal rollers substantially elliptical or V-shaped in axial section, less than a sphere,

whereby, first, any desired degree of hardness and strength may be secured; second, the roller conforms to the form of the groove in which it runs and cannot shift the position of its axis of rotation; third, its curved side conforms closely to the curve of the groove in which it runs, and therefore its direction of advance is changed by friction remote from its periphery; fourth, because it conforms to the form of the groove both vertically and horizontally, it cannot change the radial position of its axis.

My invention relates to an improvement in casters for furniture and kindred articles; and it consists in the use and adaptation of a new kind of anti-friction roller between the upper and lower portions or plates of the caster, as hereinafter more fully set forth.

In the drawings, Figure 1 represents the complete caster, viewed sidewise; Fig. 2, a vertical interior crossseetion of the same upon line a: x of Fig. l,'showing the position of the rollers in the grooves and the lower inner ledge to remove it from contact with the sprue upon the inside of the rollers. Fig. 3 shows the upper sideof the lower plate with some of the rollers in the groove. Fig. 4 is a face view of the roller, and Fig. 5 is a crosssection of the same.

Like letters indicate like parts in both the drawings and specification.

The two sections of the. caster, A and B,

have 'annular corresponding grooves upon their inner faces of the form in reverse of the periphery of the roller C, these grooves being usually near the outer diameter of the plates or sections of the caster. The roller 0 is preferably in the form, when seen in crosssection, of a nearlyfiat ellipse, but may be varied more or less. as found desirable, pro vided it has aperipherycorresponding to and adapted to run in the annular grooves in the same without liberty to change the position of its axis of rotation, which function is desirable, because I usually cast my rollersin molds with a side attachment to the patterngate, as shown atb in the drawings; In breaking these rollers from the gate more or less of a sprue or roughness will remain upon the roller; but by mounting therollersin grooves, as shown, and having the inner ledge of the groove at a, as seen in Fl 2, somewhat lower than the outer one, the roughness upon the roller, as seen at b, Fig. 5, is kept clear of coming in contact with any portion of the plates, and thus leaves a perfect roller in all of its acting parts, capable of being made cheaply and sufficiently perfect in molds of metal or other material without the necessity of any other finish than what is done in the tumbling or polishing box. Such cast rollers can be chilled or made of hard iron that will not wear or crush in use, however great the pressure upon them. Therefore What I consider to be new, and desire to secure by Letters Patent, is as follows:

1. A furniture-caster havingannular corresponding grooves upon the inner faces of its top and bottom plates, ofelliptical or V-shaped form in cross-section, in combination with anti friction rollers with peripheries corresponding with the grooves in the plates, all arranged and operating substantially as and for the purl pose specified.

2. A furniture-caster having grooved plates for anti-friction rollers, with the inner ledges of the grooves lower than the outside ones, substantially as and for the purpose specified.

3. A furniture-caster having annular corresponding grooves in the opposing faces of the upper and lower plates, said grooves being elliptical or V-shaped in transverse section, and having their ledges on one side more widely separated than their ledges on the other side, combined with cast-metal rollers having an elliptical or V-shaped cross-section in the plane of the axis corresponding with the crosssectionof said grooves, and having the axial sprues still adhering, whereby cast-metal rollers may be employed without dressing, and the form of the roller conform to the form of the groove without possibility of shifting its axis of'revolution or encountering friction on the side to destroy the figure of the bearingsurface.

DAVID J. POWERS.

Witnesses:

A. L; GRIFFETH, GUY A. 1VIALOOM. 

